A man who slipped past security and boarded a commercial airliner without a ticket at Dallas/Fort Worth International Airport was trying to stop his girlfriend from leaving, airport police said on Tuesday.

Damarias Cockerham, 25, said he walked through a Transportation Security Administration screening area Sunday night without identification or a boarding pass and was not blocked by an agent, according to a police report.

Cockerham, from the Dallas suburb of Garland, ran onto American Airlines Flight 1013 to Guatemala City because, "he didn't want his girlfriend going down there and being with the wrong guy," the police said.

An airline agent called airport police, who arrested the man on criminal trespassing charges before the flight left. He had parked his vehicle at a curbside terminal entrance before entering the airport.

A TSA spokesman said on Monday that the agency was working with the airport to evaluate passenger security checkpoints and had added barriers following the incident.

A man who slipped past security and boarded a commercial airliner without a ticket at Dallas/Fort Worth International Airport was trying to stop his girlfriend from leaving, airport police said on Tuesday.Damarias Cockerham, 25, said he walked through a Transportation...